1. Field of the Invention
The present invention relates to a printing control method and apparatus in a printing system and, more particularly, to a printing system which is constituted by a host computer and printing apparatus connected via two-way communications, and in which the host computer corrects data in accordance with a calibration request coming from the printing apparatus, and a printing control method and apparatus.
2. Related Background Art
The output images of a printing apparatus change depending on changes in environmental conditions such as temperature, humidity, and the like. If the printing apparatus is of an electrophotographic type, visible images formed change or deteriorate due to deterioration or the like of expendables such as a drum, toner cartridge, and the like. The conventional printing apparatus executes calibration for correcting such changes or deteriorations of images. In the calibration, a controller unit generates correction data in response to a calibration request from an engine unit, and corrects image data.
However, such calibration done in a printer can execute only limited kinds of corrections. For example, when the densities of the respective colors are to be corrected, a binary printer corrects data in the process of generating binary image data to be output. More specifically, in order to match the density data of an original image to be output with those recorded by the current printer in correspondence with the original density data, the controller unit generates binary image data to be input to the engine unit on the basis of the original image in consideration of the density differences.
For this reason, when the host computer binarizes data and transmits binary image data to the printing apparatus, the controller cannot detect the density differences between the original image and output image, and calibration in the printer cannot sufficiently correct data.